A shadow mask or a tension mask is part of the CRT faceplate panel assembly and is located in proximity to a luminescent screen formed on the interior surface of the viewing faceplate. As is well known in the CRT art, the mask acts as a color selection electrode, or parallax barrier, which ensures that each of the three electron beams generated by an electron gun, located in a neck of the CRT, lands only on its assigned phosphor deposit. The conventionally curved shadow mask, which is not under tension, is usually supported within a frame that is secured within the faceplate panel. Typically, the conventional shadow mask has a thickness of about 0.15 mm (6 mils) and has a transmission, in the center portion thereof, of about 18 to 20%. A uniaxial tension mask, having parallel grid elements that extend in only one dimension and are laterally spaced apart with the same lateral spacing as the conventional shadow mask, has an inherently higher transmission because of the absence of lateral connecting tie bars. One such mask is described in U.S. Pat. No. 3,638,063, issued on Jan. 25, 1972 to Tachikawa et al. That tension mask is disclosed to be formed of grid elements having a width of 0.5 mm (19.7 mils) and a thickness of 0.1 mm (3.9 mils). A problem with tension masks is that the grid wires permanently expand during the CRT manufacturing operation, for example during frit sealing of the faceplate to the funnel of the CRT envelope where the sealing temperature is about 435.degree. C., or higher. To prevent sagging of the grid wires after such expansion, the conventional approach is to provide sufficient frame compliance to maintain the necessary tension on the grid wires even after the wires are elongated during the sealing operation. However, depending on the materials selected for the grid wires and the frame members, the grid wires can experience such elongation at frit sealing that it may be difficult to provide sufficient frame compliance to maintain the necessary tension on the grid wires during normal tube operation. Accordingly, it is desirable to pre-stress the grid wires to induce a time dependent permanent strain, or elongation, of the material caused by stress, hereinafter referred to as creep, before the tension mask is mounted into the faceplate panel of the CRT.